(1) Field of the Invention
The present invention pertains to the construction of a manually operated trigger sprayer in which the conventional metal coil spring is replaced with a plastic spring that is an integral part of the pump piston rod and the pump piston is connected to the piston rod by a ball and socket connection.
(2) Description of the Related Art
Handheld and hand pumped liquid dispensers commonly known as trigger sprayers are used to dispense many household products and commercial cleaners. Trigger sprayers have been designed to selectively dispense the liquids in a spray, stream, or foaming discharge. The trigger sprayer is typically connected to a plastic bottle that contains the liquid dispensed by the sprayer.
A typical trigger sprayer includes a sprayer housing that is connected to the neck of the bottle by either a screw thread connection or a bayonet-type connection. The sprayer housing is formed with a pump chamber and a vent chamber, a liquid supply passage that communicates the pump chamber with a liquid inlet opening of the sprayer housing, and a liquid discharge passage that communicates the pump chamber with a liquid outlet opening of the sprayer housing. A dip tube is connected to the sprayer housing liquid inlet opening to communicate the pump chamber with the liquid contents of the bottle connected to the trigger sprayer.
A nozzle assembly is connected to the sprayer housing at the liquid outlet opening. Some nozzle assemblies include a nozzle cap that is rotatable relative to the sprayer housing between an “off” position where liquid discharge from the trigger sprayer is prevented, and one or more “on” positions where liquid discharge from the trigger sprayer is permitted. In addition, known nozzle assemblies can affect the liquid discharged by the trigger sprayer to discharge the liquid in a spray pattern, in a stream pattern, or as a foam.
A pump piston is mounted in the sprayer housing pump chamber for reciprocating movement between charge and discharge positions of the piston relative to the pump chamber. When the pump piston is moved to its charge position, the piston is retracted out of the pump chamber. This creates a vacuum in the pump chamber that draws liquid from the bottle, through the dip tube and into the pump chamber. When the pump piston is moved to its discharge position, the piston is moved into the pump chamber. This compresses the liquid in the pump chamber and pumps the liquid from the pump chamber, through the liquid discharge passage of the sprayer housing and out of the trigger sprayer through the nozzle assembly.
A metal coil spring is positioned in the pump chamber and engages with the pump piston. The coil spring biases the pump piston to the discharge position of the piston.
A vent piston is often provided with the pump piston and is mounted in the vent chamber. The vent piston moves with the pump piston between a vent closed position and a vent opened position in the vent chamber. In the vent opened position, the interior volume of the bottle attached to the trigger sprayer is vented through the vent chamber to the exterior environment of the trigger sprayer. In the vent closed position, the venting path of air through the vent chamber is closed, preventing leakage of the liquid in the bottle through the venting flow path should the bottle and trigger sprayer be inverted or positioned on their sides.
A trigger is mounted on the sprayer housing for movement of the trigger relative to the trigger sprayer. The trigger is operatively connected to the pump piston to cause the reciprocating movement of the pump piston in the pump chamber in response to movement of the trigger. A user's hand squeezes the trigger toward the sprayer housing to move the trigger and move the pump piston toward the discharge position of the piston in the pump chamber. The metal coil spring in the pump chamber pushes the piston back to the discharge position of the piston relative to the pump chamber when the user's squeezing force on the trigger is released.
Inlet and outlet check valves are assembled into the respective liquid supply passage and liquid discharge passage of the trigger sprayer. The check valves control the flow of liquid from the bottle interior volume through the liquid supply passage and into the pump chamber, and then from the pump chamber and through the liquid discharge passage to the nozzle assembly of the trigger sprayer.
The typical construction of the trigger sprayer discussed above has several separate component parts. The manufacturing of each of these individual component parts contributes to the overall cost of manufacturing the trigger sprayer. Because trigger sprayers are manufactured and sold in very large numbers, even a slight reduction in the manufacturing costs of a trigger sprayer can result in a significant overall reduction in the cost of manufacturing a large number of trigger sprayers. As a result, pistons with integral plastic springs have been designed to eliminate the metal coil springs used in conventional trigger sprayers and to reduce the number of component parts of the trigger sprayers. However, it has been observed that with the spring integrally connected to the piston, on reciprocation of the piston in the liquid pump chamber, the spring will exert force components on the piston that will tend to move the piston away from its coaxially aligned position relative to the pump chamber. This could distort the sealing engagement of the piston in the pump chamber and cause liquid to leak from the pump chamber on reciprocating movements of the piston.